I do not thank, that coloar 11 or 12 (= blue) is "ugly". But you can change this colour, when you click on -> Gamers.IRC -> Load Theme...

Gamers.IRC does not send any advertising to a channel when you part it. Its sends one when you quit. In oder to change this:
Tell the channelops to set mode +u
or: alt+o -> IRC -> Messages -> Quit Message

Gamers.IRC does not have so many bugs you think. The setup works fine.